In a demand/supply operation of an electric power system constituted only by an electric power source in which an electric power generation output is controllable such as conventional nuclear power generation and thermal power generation, a demand/supply plan is created as follows. That is, an electric power company calculates an output allocation in correspondence with an operation characteristic for each electric power generator of nuclear power generation, thermal power generation, or the like being an electric power source which is controllable in correspondence with a change of an estimated electric power demand. As a result, a demand/supply plan which maintains and secures a stable supply and an economical operation is created.
In recent years, in order to cope with global environmental problems or to promote utilization of non-fossil fuel, introduction of a natural energy electric power source such as solar power generation and wind power generation into an electric power system is promoted. Since a power generation output amount of such natural energy electric power sources significantly fluctuate by a change of weather, prediction is difficult. Thus, in a case that the electric power system into which the natural energy electric power source is introduced is an object, it is difficult to appropriately calculate an output allocation of a power generator being a controllable electric power source by a conventional method for creating a demand/supply plan.
In the natural energy electric power source, it is considered that numerous electric power sources such as a household solar power generation equipment and so on are installed not only in a bulk power system side but also in a power distribution system side. Since the power generation output of solar power generation changes depending on shining of the sun and weather, grasping a change is not easy. In addition, in solar power generation, there is a possibility that securing of a reserve power generation output (reserve power) and frequent changes of a current become necessary in order to prepare for a demand change.
In the above-described conventional method for creating the demand/supply plan, when a large amount of natural energy power sources are installed in the electric power system, it becomes difficult to appropriately calculate the output allocation of the power generator of the controllable power source due to a fluctuation of the power generation output of the natural energy electric power source. Further, there is a possibility that an electric power demand/supply plan created by the conventional method for creating the demand/supply plan cannot satisfy a constraint regarding a reserve power for preparing for a demand change and a constraint of a current change in which frequent changes of a current of a power transmission line is taken into consideration.
However, conventionally, it has been difficult to appropriately evaluate an electric power demand/supply plan created for an electric power system into which a natural energy electric power source is introduced, such as whether or not the electric power demand/supply plan created for the electric power system into which the natural energy electric power source is introduced satisfies the constraint regarding the reserve power and the constraint of the current change.